🚨 Abdominal Trauma
Mechanisms · Diagnostics · Indications for Surgery · Organ-Specific Control · Damage Control Surgery — MRCS high-yield notes
The Surgical Abdomen in Trauma
For the purposes of trauma surgery, the abdomen extends from the nipple line (4th intercostal space in expiration) down to the perineum. This is broader than the surface anatomy definition and explains why lower thoracic injuries can cause abdominal organ damage.
Blunt trauma is classically caused by road traffic collisions (steering wheel/seatbelt impacts) or falls. It produces three types of force:
- Crush / compression forces — direct organ damage from impact
- Deceleration / shearing forces — tears occur at fixed points of attachment (e.g., liver at the ligamentum teres, bowel at the ligament of Treitz)
- Burst injuries — sudden rise in intraluminal pressure ruptures hollow viscera
Most Frequently Injured Organs in Blunt Trauma
| Organ | Frequency | Key Mechanism |
|---|---|---|
| Spleen | 40–55% | Direct blow to left lower ribs (9–11); highly vascular and fragile |
| Liver | 35–45% | Deceleration tears at hepatic vein–IVC junction; direct compression |
| Small Bowel | 5–10% | Shearing at fixed points (ligament of Treitz, ileocaecal valve); seatbelt injuries |
| Mesentery | Common with bowel | Deceleration tears mesenteric vessels → devascularisation without visible perforation |
| Kidney | Common | Retroperitoneal; direct flank blow; deceleration tears renal pedicle |
| Pancreas / Duodenum | Uncommon but high morbidity | “Handlebar” crush against spine; commonly missed on initial assessment |
The Seatbelt Sign
A seatbelt bruise across the abdominal wall should raise immediate suspicion for underlying hollow viscus injury (small bowel, mesentery) and Chance fracture (flexion-distraction fracture of the lumbar spine). Bowel injuries from seatbelts are frequently missed because peritonism may take 6–12 hours to develop as bowel contents leak slowly. If a seatbelt sign is present, have a very low threshold for CT.
Stab Wounds vs Gunshot Wounds
| Stab Wounds | Gunshot Wounds (GSWs) | |
|---|---|---|
| Energy transfer | Low energy — damage limited to direct path of blade | High kinetic energy — cavitation effect damages tissue beyond the bullet path |
| Most injured organs | Liver, small bowel, diaphragm, colon | Small bowel, colon, liver, major abdominal vessels |
| Peritoneal violation | ~30% of anterior stab wounds do not penetrate peritoneum | Most GSWs traversing the abdominal cavity require laparotomy |
| Initial management | Selective — local wound exploration + CT ± laparoscopy if stable | Low threshold for immediate laparotomy if trajectory crosses peritoneum |
| Diaphragm injury | Commonly missed — left diaphragm most frequently injured; may present late as herniation | Any trajectory near the thoracoabdominal junction warrants diaphragm evaluation |
Cavitation and Kinetic Energy
The tissue damage from a gunshot wound is proportional to the kinetic energy transferred: KE = ½mv². Velocity is squared, meaning high-velocity weapons (rifles) cause exponentially more damage than low-velocity handguns. Cavitation creates a temporary cavity larger than the bullet itself — bowel, vessels, and solid organs remote from the bullet track may still be injured. Always assume more damage than is visible.
FAST ultrasound and DPL both fail to reliably detect retroperitoneal injuries. These are the organs most likely to be missed in the initial assessment. Memorise them with the mnemonic SAD PUCKER:
Suprarenal (Adrenal) Glands
Bilateral; adrenal haemorrhage can cause Addisonian crisis post-trauma
Aorta & IVC
Major retroperitoneal vascular injury; rapidly fatal; requires immediate operative control
Duodenum
D2/D3 crushed against spine in “handlebar” injuries; duodenal haematoma may present late
Pancreas
Retroperitoneal; blunt crush → transection at neck over spine; amylase may be initially normal
Ureters
Deceleration injury at ureteropelvic junction; haematuria may be absent; CT urogram required
Colon (ascending & descending)
Retroperitoneal portions; injury may not cause immediate peritonism
Kidneys
Most common retroperitoneal injury; classified by AAST grade; haematuria supports diagnosis
Oesophagus (distal)
Rare; usually penetrating injury; missed → mediastinitis
Rectum
Extraperitoneal portion in pelvis; penetrating pelvic trauma; digital rectal exam mandatory